Fuse blowing device for igniter tubes



H. KLEMPERER NITER TUBES Feb. 29, 1944.

FUSE BLOWING DEVICE FOR 16 Filed. March 25, 1941 r A A A, W

\NvEN-ro HANS .KLEMPERER,

ATTY.

trical apparatus. In such a Patented Feb. 29, 1944 2,342,673 FUSE nmwmo DEVICE FOR mm'rEa TUBES Hans Klemperer, Belmont, Raytheon Manufacturing a corporation of Delaware Mass,

Mass, assignor to Company; Newton,

Appllcation March 25, 1941, Serial No. 385,075

13 Claims.

This invention relates to an arrangement for insuring the melting of the fuse wires in series with igniter elements in an igniter tube of the type which I have disclosed and claimed in my copending application, Serial No. 261,399, filed March 11, 1939, for an improvement in Elec tube a definite minimum amount of power is necessary in order to blow the fuse upon the breakdown of the insulation of the igniter element associated therewith. In some instances the igniting impulsesupplying circuit is insumcient for maximum reliability of operation.

An object of this invention 'is to insure the melting of each fuse upon the breakdown of the insulation of the associated igniter-element.

Another object is to provid a separate source of power for blowing the fuse.

Another object is to cause the source of fuseblow'mg power to operate in such a way as to rovid minimum interference with the initiation of the arc spots on the cathode of the tube and with the normal operation of the tube.

A still further. object is to provide simple and reliable means for accomplishing the foregoing objects.

The foregoing and other objects of this invention will be best understoodfrom the followin description of an exempliflcation thereof, reference being bad to the accompanying drawing. wherein the figure is ing one embodiment of my invention.

In the arrangement illustrated, i represents a controlled ignition type of discharge tube of the kind more fully described and claimed in my copending application above referred to. This tube consists of an envelope containing a pool type cathode 2, preferablycf mercury, although other materials. such as gallium and the like, could be used. An anode 3 is adapted to cooperate'with the cathode. Adjacent the cathode is a plurality of igniter elements 4. These igniter elements consist of a conductor insulated and separated from the pool cathode 2 by a layer of insulation, such as glass. The outside surface of the glass layer is in contact with the surface of the mercury pool 2. The conducting portion of each or the igniter elements 4 is connected through a fuse 5 to a common conductor 8 which constitutes the lead-in conductor for the igniter elements 4. Each of the fuses 5 is designed so as to fuse at a relatively low current of the order of 100 milliamperes. The tube l is adapted to be energized from a pair of terminals 1 and l which are to be connected to a suitable source a circuit diagram illustrat-- of alternating current. The anode 2 may be connected directly to one of the terminals 8, while the cathode 2 is connected through a suitable load device to the terminal I.

In order to supply the igniting elements 4 with igniting impulses, an ignition transformer I0 is provided. This transformer has a secondary II which is connected between the igniting elements 4 and the cathode 2. The primary winding l2 of the transformer I0 is supplied with peaked igniting impulses from apeaking transformer l3, which in turn is energized through aQphase-shifting device 14 from the alternating current terminals 1 and 8. The phase-shifting device l4 may be adjusted so that each voltage peak occurs at the desired portion of the alternating voltage cycle applied to the 4 tube I.

A fuse-blowing transformer II is provided for the purpose of supplying power for blowing each fuse 5 upon breakdown of the insulation on its associated igniter element 4. The transformer l5 has a primary winding l8 which is energized from the alternating current terminals I and 8. ll of the transformer l5 The secondary winding is connected in series with a rectifier tube l8 between the igniting elements 4 and the cathode 2. The rectifier tube l8, which may be of the gas or vapor-filled type, is preferably provided with a thermionic cathode l9 connected in series with the secondary H to the igniter elements 4. The rectifier tube 18 is also provided with an anode 20 connected directly to the cathode 2.

When the system described above is energized, igniting impulses will be supplied through the members I4, l3, l2 and II to the igniting elements 4, and an arc spot will .be initiated on the cathode 2 during each conducting half cycle applied to the tube 1 at the proper phase angle, as determined by the phase-shifting device l4. If, however, the insulation on any one of the igniter elements 4 breaks down, a considerable decrease in the resistance or impedance through the igniter circuit is created. Thereupon when the voltage on the secondary I1 is in the correct polarity, the rectifier It will conduct a suiilcient amount of current which will pass through the fuse 5 associated with the defective igniter element 4, causing said fuse to melt and disconnect the defective igniter. Usually it is desirable to place a resistance 2| in series with the igniter elements 4 so as to limit the current supplied through the rectifier tube l8 to a value which is insuflicient to establish or maintain a true u are on the cathode 2. The resistance 2|, for

example, may be of such a value as to limit the current supplied through the rectifier tube It! to the order of 100 or 200 milliamperes. Under these conditions it is relatively unimportant as to the polarity of conduction of the rectifier H or of the voltage on the secondary winding II. The presence of the resistance 2| will prevent the power supplied from the secondary winding 11 from establishing or maintaining an are spot on the cathode 2 at somemndesirable point on the voltage wave supplied to the tube I. However, it is desirable that the melting of the fuse wire I should occur during -th inactive portion of the alternating voltage cycle applied to the tube I, namely that half cycle in which the anode 3 is negative. For this purpose the phase of the voltage applied to the I 8 is reversed, as indicated at 22, and the polarity of the rectifier I8 is so chosen that current flows through said rectifier through the defective igniter element 4 only during the inactive half cycle of the voltage wave applied to the tube I. In addition, it is often desirable to limit the voltage applied through the secondary winding I! so that a voltage less than that required to create and support an are spot on the cathode 2 is impressed between the conductor 6 and said cathode. For example, if 'the voltag drop through the tube I8 is of the order of 10 volts, the voltage on the secondary winding i! may have a peak value of about volts, leaving only five volts to be impressed between the conductor 6 and the cathode 2, which while sufficient to blow each fuse I, when necessary is insufiicient to create and support an are spot on the cathode 2.

The system which I have described above insures that upon breakdown of any one of the igniter elements 4, said igniter element will be disconnected from the system within the next .half cycle so that the tube I is conditioned to start normal operation during the next normal conducting half cycle of the voltage wave supplied thereto.

Of course it is to be understood that this invention is not limited to the particular details as described above as many equivalents will suggest themselves to those skilled in the art. For example, other arrangements for supplying igniting impulses to the igniter elements 4 could be devised, and also the tube I could be connected in any type 01 system in which periodic ignition is desired. It is accordingl desired that the appended claims be given a broad interpretation ,ecommensurate with the scope of the invention within this art.

What is claimed is:

1. In combination, an element opposing flow of current, means in series witha fusible member for impressing a first-voltage across said element, which voltage during operation may attain a value suflicient to produce breakdown and flow of current through said element; said means having sufficiently high impedance to limit the current flow upon said breakdown to a value insufficient to fuse said fusible member, and separate means in series with said fusible member for impressing a second voltage across said element, said second voltage being insufficient to cause breakdown of said element, said separate means having sufficiently low impedance to pass a sufficient current through said fusible member to fuse said member upon breakdown of said element.

2. In combination, an insulating element opposing flow of current, means in series with a primary winding fusible member for impressing a first-voltage across said element, which voltage during operation may attain a value suflicient to produce breakdown and flow of current through said element, said means having sufficiently high impedance to limit the current flow upon said breakdown to a value insufficient to fuse said fusible member, and separate means in series with said fusible member for impressing a second voltage across said element, said second voltage being insuflicient to cause breakdown of said element, said separate means having sufliciently low impedance to pass a sufficient current through said fusible member to fuse said member upon breakdown of said element.

3. In combination, a discharge tube comprising an arc type cathode, an anode, and an igniter element for initiating an are spot on said cathode, means in series with a fusible member for impressing an igniting voltage between said igniter element and said cathode, and separate means for passing sufficient current through said fusible member to fuse said member upon breakdown of said igniter element.

4. In combination, a discharge tube comprising an arc type cathode, an anode, and an igniter element comprising a conductor insulated and separated from said cathode by an insulating layer for initiating an are spot on said cathode, means in series with a fusible member for impressing an igniting voltage between said igniter element and said cathode, and separate means for passing sufficient current through said fusible member to fuse said member upon breakdown of said insulating layer.

5. In combination, a discharge tube comprising a plurality of igniter elements for initiatin an arc spot on said cathode, a fusible member in series with each of said igniter elements, means for impressing an igniting voltag between each of said igniter elements and said cathode through the associated fusible member, and separate means for passing sufllcient current through each fusible member to fuse said member upon breakdown of its associated element."

6. In combination, a discharge tube comprising a plurality of igniter elements each comprising a conductor insulated and separated from said cathode by an insulating layer for initiating an are spot on said cathode, a fusible member in series with each of said igniter elements, means for impressing an igniting voltage between each of said igniter elements and said cathod through the associated fusible member, and separate means for passing sufficient current th ough each fusible member to fuse said memberu n breakdown of its associated insulating layer.

'7. In combination, a rectifying discharge tube comprising an arc type cathode an anode, and an igniter element for initiating an are spot on said cathode, means for impressing an alternating voltage between said cathode andanode, means in series with a fusible member for impressing an igniting voltage between said igniter element and said cathode during the normally-conductive half cycle of said alternating voltage, and means for impressing another voltage source between said igniter element and said cathode in series with said fusible'member during the normally nonconductive half cycle of said alternating voltage,

said voltage source being adapted to pass sufllcient current through said fusible member to fuse said member upon breakdown of said igniter element.

8. In combination, a rectifying discharge tube comprising an arctype cathode, an anode, and an igniter element comprising a conductor insulated and separated from said cathode by an insulating layer for initiating an are spot on said cathode, means for impressing an alternating voltage between said cathode and anode, means in series with a fusible member for impressing and igniting voltage between said igniter element and said cathode during the normally-conductive hair cycle of said alternating voltage, and means for impressing another voltage source between said igniter element and said cathode in series with said fusible member during the normally non-conductive half cycle of said alternating voltage, said voltage sourcebeing adapted-to pass sumcient current through said fusible member to fuse said member upon breakdown of said insulating layer. v 9. In combination. a discharge tube comprising an arc type cathode, an anode, and an igniter element for initiating an are spot on said cathode, means in series with a fusible member for impressing an igniting voltage between said igniter element and said cathode, and a rectifier connected in series with a source of alternating voltage cohnected'between said igniter element and said cathode in series with said fusible member, said rectifier and source beingadapted to pass sumcient current through said fusible member to fuse said member upon breakdown of said igniter element. 7

id. In combination, a discharge tube comprising an arc type cathode, an anode, and an igniter element comprising a conductor insulated and separated from said cathode by an insulating layer for initiating an are spot on said cathode, means in series with a fusible member for impressing an igniting voltage between said igniter element and nected in series with a source of alternating voltage connected between said igniter element and said cathode in series with said fusible member, said rectifier and source being adapted to pass sumcien't current through said fusible member to fuse said member upon breakdown of said insulating layer. Q 11. In combinati a rectifying discharfle tube comprisinc an arc type catbod an anode, and

' ing an arc type said cathode, and a rectifier conan igniter'element for initiating an arc spot on said cathode, means in series with a fusible mem her said ignite; element and said cathode during the normally-conductive hali cycle of said alternating voltage, and a rectifier connected in series with a source of alternating voltage connected between said igniter element and said cathode in series with said fusible member, said rectifier and source being adapted to pass sufllcient current through said iusible member to fuse said member upon breakdown of said igniter element, said rectifier being of a polarity to supply current to said ignites element during the normally non-conductive period of said discharge tube.

12. In combination, a discharge tube compriscathode, an anode, a plurality of igniter elements for initiating an are spot on said cathode, a fusible member in series with each of said igniter elements, means for impressing an igniting voltage between each of said igniter elements and said cathode through the associated fusible member, and a rectifier connected in series with a source oi .alternatingvoltage connected between said igniter elemehts and said cathode in series with said fusible members, said rectifier and source being adapted to pass suflicient current through each of said fusible members to fuse said member upon breakdown of its associated igniter element.

' 13. In combination, a discharge tube comprising an arc type cathode, an anode, and a plurallty oi ignites elements each comprising a conductor insulated and separated from said cathode by an insulating layer for initiating an are spot on said cathode, a fusible member in series with each of said igniter elements, means for impressing an igniting voltage between each of said igniter elements and said cathode through the associated fusible member, and a rectifier connected in series with a source of alternating voltage connected between-said igniter element and said cathode in series with said fusible member, said rectifier and source being adapted to pass sufllcient current through each of said fusible members to fuse said member upon breakdown of its associated insulating layer.

HANS ERE for impressing an igniting voltageabetween 

